Industry experts say that technology has advanced to a point that a review of the ban on using PUB water in garden sprinklers would be worthwhile.

Water sprinkler (Photo: Justin Sullivan / Getty Images North America / AFP)

SINGAPORE: A few months ago, Sam Lee* showed his client, the owner of a Good Class Bungalow (GCB), his final proposal to develop her garden. He had put it together with advice from irrigation and water harvesting specialists because the client had indicated she wanted to use collected rain water for the sprinkler system.

The final cost came to about S$90,000. However, that was too expensive for the client, Mr Lee said, and she decided to cancel the harvesting system.

The regulation requires anyone using sprinklers to water their landscapes to have their own source of water - from harvested rainwater or ponds, for example - unless they have permission to tap on PUB supplies. PUB told Channel NewsAsia this clause has been in the Public Utilities (Water Supply) Regulations since the 1970s.

The rule is known among golf course operators: Those that responded to Channel NewsAsia's queries said they water their fairways and greens using harvested water.

90% OF CLIENTS USE PUB WATER FOR SPRINKLERS: LANDSCAPE SPECIALIST

When connecting sprinklers to harvested rainwater, Mr Lee said a break-out tank needs to be built on the premises. This is to ensure the non-potable water does not contaminate drinking water.

A pressure pump also needs to be attached to distribute the rainwater through the sprinkler system. Irrigation specialist David Chua said the end result is costly.

“Often, these tanks have to be underground,” said Mr Chua, who is director of Christensen Irrigation, a global irrigation company which operates in Singapore.

“It is usually underground because space is a premium and also because of aesthetics. And because it is underground, it will be expensive to build. So I would think harvesting rainwater would only be confined to a very select few home owners, only for the GCBs. For the terraced and semi-detached houses, it's unlikely.”

Mr Lee said 90 per cent of clients who approach him to develop their gardens end up not complying with this rule even though he makes sure they are aware of it.

“I need to ensure my clients know what they’re getting into. If you use tap (water), you are infringing (the rule) … but it’s very difficult to convince them.”

He said the plans for the sprinkler system are not indicated in the project’s plumbing plans. Once the authorities approve the plans, the sprinkler system is installed and connected to a PUB tap.

In a statement to Channel NewsAsia, PUB said it has a surveillance team to check for non-compliance. It said that when feedback is received that water sprinklers are being used, it will investigate the source of water.

“If they are using PUB-supplied water, the premises will have to remove the sprinkler system,” PUB said.

“Failure to comply can result in a fine not exceeding S$10,000 or imprisonment for a term not exceeding 12 months or both and, in the case of a continuing offence, a further fine not exceeding S$250 for every day or part thereof.”

Mr Lee said he understands PUB’s rationale behind the need for a break-out tank to prevent contamination and not tapping on potable water because it is an important resource in Singapore.

But compared to home owners using hoses to indiscriminately water their plants with PUB water, he said allowing irrigation methods such as sprinklers could result in more efficient use of water.

MANUAL WATERING USING PUB WATER LESS EFFICIENT THAN SPRINKLERS?

Out of more than 10 landed properties along Andrew Road that Channel NewsAsia approached, a majority of home owners said they use hoses to water their gardens and plants. Two home owners that used water sprinklers for irrigation declined to be interviewed when asked if they had their own water source.

Mr Lee said he thinks that using sprinklers is more efficient: “Once I turn on the tap, within a minute, each sprinkler will have the same pressure, and will be watering at that point. Which means if I set (the timer) for five minutes, the 15m to 20m length of plants will be watered at the same time.”

Mr Chua agreed: “I would think it can be as much as 50 per cent more water consumed when you water using a hose." 

He said using hoses also does not allow plants to receive the amount of water they need.

“In Singapore, my feeling is that the main cause of water wastage is not about using pop-up sprinklers or drip lines,” Mr Chua said.

“It is actually managing watering schedules. For example, the home owner or landscape maintenance supervisor may tell their worker or helpers: ‘Hey, please water every day’. But do you need to water every day? My answer is no.”

Experts say sprinklers are also more efficient as they allow landscape planners to supply water based on the needs of the plant. ( Photo: Monica Kotwani)

For gardens with plants of different varieties and sizes, Mr Lee and Mr Chua agreed that use of sprinklers can be more efficient.

Mr Chua said drip lines are used to cover an even area, for example, in a planter bed with the same type of plants. But in a landscape with a variety of plants, it makes sense to use pop-up sprinklers.

“If you have a tall shrub with long stems, the emitter can be placed at the base of the plant, and water laterally and it can be quite effective,” he said.  

SPRINKLER TECHNOLOGY HAS COME A LONG WAY: IRRIGATION EXPERT

Mr Chua said that as the regulation has been in place since the 1970s, it could be time to review the ban on using PUB water in sprinklers. While sprinklers may have been less efficient in the past, technology has come a long way.

“In the past, I think the impact sprinklers, which did not give a very good distribution of water, could be a good reason to say: ‘This is not very efficient, yes, we should put it aside’,” he said.

“But today, where every other country in the world uses sprinklers - and the manufacturers come from the US where they have done a lot of research and they have huge farms - I would think that the sprinkler technology is very advanced and watering distribution is very even.”

Meanwhile, he said more could be done to educate home owners about using water in their gardens. 

“It’s not about the implementation,” he said. 

“What they will end up doing if you prevent sprinklers is that they will ask their helpers to manually water the turf, which will waste even more water.”

Source: CNA/mo